Thoracic Definition

The term thoracic means of or pertaining to the thorax. Thorax, in medical terminology, refers to the chest region of the body. The thorax, or chest region, encompasses everything from the neck down to the diaphragm.

Thoracic Region

The thoracic region of the spine begins at the base of your neck and ends around the bottom of your rib cage, just above your lower back. The thoracic region of the spine, the upper back, is located below the cervical region (neck) and above the lumbar region (lower back).

How Many Thoracic Vertebrae Are There?

Humans have 12 thoracic vertebrae. In keeping with the naming convention of all vertebrae, they are called T1 through T12.

Not all mammals have 12 vertebrae in the thoracic region. The amount can vary greatly with some species having 11, 13, 25, etc.

Note: Remember from Part 1 of the Spine Anatomy series that the vertebrae are named with a letter (signifying the spinal region) and a number. For each region (cervical, thoracic and lumbar) the number starts at 1 with the topmost vertebra, and continues with 2, 3, etc counting down toward the bottom of the spine.

Thoracic Vertebrae

The thoracic vertebrae are larger than the cervical vertebrae and smaller than the lumbar vertebrae. In the thoracic region, the size of the vertebrae increase as you go down the body.

In general, the thoracic vertebrae anatomy differs from other regions of the spine to allow for movement next to the ribs. The main two differences are that the thoracic vertebrae have:

Facets on either side of the vertebrae body to allow for movement next to the heads of the ribs

Facets on either side of the transverse processes to allow for movement next to the tubercles of the ribs (a bony prominence on each rib)

Note: T11 and T12 do not contain facets on the transverse processes.

Thoracic Nerves

There are 12 thoracic nerves. Their naming convention is similar to that of the vertebrae. The thoracic nerves are labeled T1-T12. The T1 nerve branches out from the spinal cord just below the T1 vertebra, the T2 nerve branches out from the spinal cord just below the T2 vertebra and so on.

The thoracic nerves control the muscles within the our chest and parts of our abdomen.

Stay tuned for next week as we’ll continue our overview of the spine’s anatomy.

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